Carbon monoxide (CO) is a clear, odorless and tasteless gas. It’s made by insufficient fuel combustion frequently caused by a lack of oxygen. In your house, appliances that use natural gas, charcoal, wood or kerosene are susceptible. Especially if they are not working correctly or have been installed wrong.
Vehicle exhaust fumes from nearby garages, as well as malfunctioning fireplaces may also be a carbon monoxide source. CO is poisonous to the body and is lethal at high levels or with prolonged exposure.